Intro To 'pathchk' Command In Linux

2024-02-21 - By Robert Elder

I use the 'pathchk' command to check if a file or path name is portable:

pathchk -P -p my-example-path#1

pathchk: nonportable character ‘#’ in file name 'my-example-path#1'

Check Portability Of Path Names

The 'pathchk' command can check for a number of different portability issues with file and path names:

info pathchk

...
   For each NAME, ‘pathchk’ prints an error message if any of these
conditions is true:

  1. One of the existing directories in NAME does not have search
     (execute) permission,
  2. The length of NAME is larger than the maximum supported by the
     operating system.
  3. The length of one component of NAME is longer than its file
     system’s maximum.
...

This command will check for path names that are too long to be POSIX compliant:

pathchk -P -p aaaaaaaaaaaaaaa

pathchk: limit 14 exceeded by length 15 of file name component ‘aaaaaaaaaaaaaaa’

and this command will check for an empty file name:

pathchk -P -p ''

pathchk: empty file name

Checking For Leading Dash Characters

The 'pathchk' command can also check for file names that contain a leading dash character:

pathchk -P -p -foo

pathchk: invalid option -- 'f'
Try 'pathchk --help' for more information.

and neither does this one:

pathchk -P -p '-foo'

pathchk: invalid option -- 'f'
Try 'pathchk --help' for more information.

or this one:

pathchk -P -p "-foo"

pathchk: invalid option -- 'f'
Try 'pathchk --help' for more information.

This command however, does work:

pathchk -P -p -- -foo

pathchk: leading '-' in a component of file name '-foo'

since it uses the special double dash argument that indicates the end of optional arguments as described in the POSIX specification (see Guideline 10).

Checking For Directory Permission Issues

You can also check for 'directory' permission issues:

mkdir foo
touch foo/boo
chmod u-x foo

ls -ld foo

drw-rwxr-x 2 robert robert 4096 Feb 10 17:07 foo

pathchk foo/boo

pathchk: foo/boo: Permission denied

Filesystem Length Limits

Some filename limits are imposed by the filesystem. You can check for file name constrains that are based on operating system limits instead of POSIX limits:

pathchk aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

pathchk: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: File name too long

The '--portability' Flag

The GNU Core Utils implementation of the 'pathchk' command also supports the 'portability' flag, that can be used in place of the two -p flags:

pathchk --portability my-example-path#1
pathchk --portability aaaaaaaaaaaaaaa
pathchk --portability ''
pathchk --portability -- -foo

pathchk: nonportable character ‘#’ in file name 'my-example-path#1'
pathchk: limit 14 exceeded by length 15 of file name component ‘aaaaaaaaaaaaaaa’
pathchk: empty file name
pathchk: leading '-' in a component of file name '-foo'

info pathchk

‘--portability’
     Print an error message if a file name is not portable to all POSIX
     hosts.  This option is equivalent to ‘-p -P’.

And that's why the 'pathchk' command is my favourite Linux command.

Intro To 'stty' Command In Linux Published 2023-10-04	$1.00 CAD Terminal Block Mining Simulation Game	Intro To 'nproc' Command In Linux Published 2023-07-15	Intro To 'comm' Command In Linux Published 2023-09-06
How To Force The 'true' Command To Return 'false' Published 2023-07-09	A Surprisingly Common Mistake Involving Wildcards & The Find Command Published 2020-01-21	A Guide to Recording 660FPS Video On A $6 Raspberry Pi Camera Published 2019-08-01	Intro To 'chroot' Command In Linux Published 2023-06-23

Why Bother Subscribing?

Free Software/Engineering Content. I publish all of my educational content publicly for free so everybody can make use of it. Why bother signing up for a paid 'course', when you can just sign up for this email list?
Read about cool new products that I'm building. How do I make money? Glad you asked! You'll get some emails with examples of things that I sell. You might even get some business ideas of your own :)
People actually like this email list. I know that sounds crazy, because who actually subscribes to email lists these days, right? Well, some do, and if you end up not liking it, I give you permission to unsubscribe and mark it as spam.